Search for Electronic Recoil Event Rate Modulation with 4 Years of XENON100 Data

TL;DR

This study analyzed four years of XENON100 data to search for periodic modulations in electronic recoil events, finding no significant dark matter signal but excluding DAMA/LIBRA's modulation as dark matter electron interactions.

Contribution

The paper presents a novel four-year analysis of XENON100 data using a profile likelihood method to search for event rate modulations.

Findings

Weak modulation signature at ~431 days with 1.9σ significance

No other significant periodicity detected

Excludes DAMA/LIBRA modulation as dark matter electron interactions at 5.7σ

Abstract

We report on a search for electronic recoil event rate modulation signatures in the XENON100 data accumulated over a period of 4 years, from January 2010 to January 2014. A profile likelihood method, which incorporates the stability of the XENON100 detector and the known electronic recoil background model, is used to quantify the significance of periodicity in the time distribution of events. There is a weak modulation signature at a period of $431^{+16}_{-14}$ days in the low energy region of $(2.0-5.8)$ keV in the single scatter event sample, with a global significance of $1.9\,\sigma$, however no other more significant modulation is observed. The expected annual modulation of a dark matter signal is not compatible with this result. Single scatter events in the low energy region are thus used to exclude the DAMA/LIBRA annual modulation as being due to dark matter electron interactions via axial vector coupling at $5.7\,\sigma$.